Re: bug? fstrim only trims unallocated space, not unused in bg's

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

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On 2017年11月19日 14:17, Chris Murphy wrote:
> fstrim should trim free space, but it only trims unallocated. This is
> with kernel 4.14.0 and the entire 4.13 series. I'm pretty sure it
> behaved this way with 4.12 also.

Tested with 4.14-rc7, can't reproduce it.
------
# btrfs fi us /mnt/btrfs/
Overall:
    Device size:		   1.00GiB
    Device allocated:		 566.38MiB
    Device unallocated:		 457.62MiB
    Device missing:		     0.00B
    Used:			 256.81MiB
    Free (estimated):		 649.62MiB	(min: 420.81MiB)
    Data ratio:			      1.00
    Metadata ratio:		      2.00
    Global reserve:		  16.00MiB	(used: 0.00B)

Data,single: Size:448.00MiB, Used:256.00MiB
   /dev/loop0	 448.00MiB

Metadata,DUP: Size:51.19MiB, Used:400.00KiB
   /dev/loop0	 102.38MiB

System,DUP: Size:8.00MiB, Used:16.00KiB
   /dev/loop0	  16.00MiB

Unallocated:
   /dev/loop0	 457.62MiB

# fstrim  /mnt/btrfs -v
/mnt/btrfs: 665.3 MiB (697597952 bytes) trimmed
------


Any special mount options or setup?
(BTW, I also tried space_cache=v2 and default v1, no obvious difference)

Thanks,
Qu

> 
> 
> [root@f27h ~]# fstrim -v /
> /: 39 GiB (41841328128 bytes) trimmed
> [root@f27h ~]# btrfs fi us /
> Overall:
>     Device size:          70.00GiB
>     Device allocated:          31.03GiB
>     Device unallocated:          38.97GiB
>     Device missing:             0.00B
>     Used:              22.02GiB
>     Free (estimated):          47.72GiB    (min: 47.72GiB)
>     Data ratio:                  1.00
>     Metadata ratio:              1.00
>     Global reserve:          65.97MiB    (used: 0.00B)
> 
> Data,single: Size:30.00GiB, Used:21.25GiB
>    /dev/nvme0n1p8      30.00GiB
> 
> Metadata,single: Size:1.00GiB, Used:791.58MiB
>    /dev/nvme0n1p8       1.00GiB
> 
> System,single: Size:32.00MiB, Used:16.00KiB
>    /dev/nvme0n1p8      32.00MiB
> 
> Unallocated:
>    /dev/nvme0n1p8      38.97GiB
> 
> 


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